Optimal design of Piezoelectric Energy Harvesters for bridge infrastructure: Effects of Location and Traffic Intensity on Energy Production

Piezoelectric energy harvesters (PEHs) can be used as an additional power supply for a Structural Health Monitoring (SHM) system. Its design can be optimised for the best performance; however, the optimal design depends on the input vibration, e.g. acceleration of a bridge due to wind loads and passing traffic. In previous studies, we have shown that optimal design tunes to some predominant frequency of the signal spectrum. However, our previous study was limited to a single location of a PEH on a bridge. In this work, we extend the rigorous optimisation framework to include the effect of the PEH's location. The optimisation framework uses the PEH plate model discretised by IsoGeometric Analysis (IGA) and coupled with the Particle Swarm Optimisation algorithm to find the designs with maximum energy outputs for many acceleration histories, extracted from the recorded dynamic response data of a real cable-stayed bridge in Australia. Then, clustering is performed to find several best candidates for the entire bridge. An additional study is performed to quantify the effect of traffic intensity on the produced energy. It is shown that variation in traffic volume throughout the 24hr time window leads to variation in optimal PEH designs. The study concludes the impact of location and traffic on energy harvesting by identifying the optimal PEH design and placement throughout the bridge structure. The results indicate that the key factors of maximising energy harvesting efficiency are related to the input excitation and the mode of vibration being excited. The position of maximum displacement in the vibration mode corresponds to the best location for energy harvesting. Also, the change in traffic intensity affects the amount of convertible mechanical energy and also directs the fundamental frequency of a PEH to shift within a specific range of frequencies to achieve the highest energy conversion.